Ecological characteristics of macrobenthic communities and their relation to environmental factors in the bays of Shandong

The benthos in four bays (Rongcheng Bay, Sanggou Bay, Jinghai Bay and Wuleidao Bay) at 19 sampling locations were investigated by taxonomy and calculating the composition, biomass, abundance and diversity indices in the summer of 2006. A total of 13 environmental variables from 19 sampling locations in four bays were analyzed by factor analysis, and spearman correlations of main environmental variables and parameters of benthos community were investigated. The 61 species of macrobenthic animals were collected in Rongcheng bay, which were the most in four bays, and the least species (23 individuals) were in Wuleidao Bay. The macrobenthic biomass in four bays was distinguished as, Wuleidao Bay >; Rongcheng Bay >; Jinghai Bay >; Sanggou Bay. The habiting density was the highest (1507.41individuals-m
^-2
) in Rongcheng Bay, and the density in Wuleidao Bay was only of 49.08 individuals-m
^-2
. Both in Rongcheng Bay and Sanggou Bay the macrobenthic Shannon Wiener indices were high, which were 1.95 and 1.49, respectively. The averages Shannon-Wiener index was 1.17 in Jinghai Bay, and only 0.40 in Wuleidao Bay. The results indicated that macrobenthic communities in Rongcheng Bay, Sanggou Bay and Jinghai Bay were distributed widely and equably, and bentic ecological environment in Wuleidao Wan was still severe and need to be improved. Factor analysis of main environmental variables in four bays indicated that accumulative contribution of the first main component was 52.19%, which was composed of the five environmental factors, dissolved phosphorus, total alkalinity, water depth, water temperature and salinity. The Spearman correlation analysis between main environmental variables and parameters of benthos community demonstrated that dissolved phosphorus, total alkalinity, water depth and water temperature were significantly correlation with the above parameters. The results suggested that there was higher impact on ecological characteristics of macrobenthic communities in the environmental gradient caused by dissolved phosphorus, total alkalinity, water depth and water temperature.